A virtual universe is a computer-based simulated environment intended for its users to inhabit and interact via avatars. A computer avatar is a personalized graphic file or rendering that represents a computer user. These avatars are usually depicted as textual, two-dimensional, or three-dimensional graphical representations, although other forms are possible (auditory and touch sensations for example). Some, but not all, virtual universes allow for multiple users.
There may be multiple virtual universes. One such virtual universe is provided by Second Life. Second Life is an Internet-based virtual universe launched in 2003, developed by Linden Research, Inc. (commonly referred to as Linden Lab). Second Life is a trademark of Linden Research, Inc.
Many companies are utilizing virtual universes for business functions such as by having on-line stores available for shopping in a virtual space. These virtual stores might sell both real merchandise and virtual goods. An avatar may be used to search for and purchase the real merchandise and virtual goods in the virtual universe in which it exists. Examples of virtual items are design tools, VU-enabled MP3 players, or code enabling unique avatar actions. Such virtual items may contain malicious scripts that either drain valuable resources from either the VU server or the resident's client computer, or exploit vulnerabilities in either the server or client code. As a result, the VU may run slower or crash.